The epsilons are not necessarily reliable indicators of data quality. DIPSO rejects points on input if they are flagged with an epsilon less than or equal to `epsmin' (which defaults to -251), leaving the spectrum in the current arrays. It is forbidden to set epsmin less than or equal -1600, since this would result in totally unflagged, certainly bad, data being acquired.
If epsmin is given a value greater than zero, then all datapoints are read into the next available stack entry, and the epsilon array into the subsequent stack entry. More subtle doctoring of the data is then possible, using USSPCLIP (q.v.). However, it is recommended that the default epsmin be accepted unless you really know what you're doing, and have good reasons to choose a different value.
DIPSO --- A friendly spectrum analysis program